1. Field of the Invention
The present invention relates generally to urine collection bags and, more specifically, to an improved anti-reflux valve for use in a urinary drainage bag to prevent back flow of urine into the drainage tube and the bladder.
2. Description of the Prior Art
In order to facilitate mobility of catheterized patients, urine collection bags are widely available in leg-mounted and abdominally-mounted varieties, as well as bed-side bags for bedfast patients. It is necessary for such urine collection bags to provide a secure connection with the flexible drainage tube that leads from the catheter. However, even with the most secure connection between the drainage tube and the urine collection bag, a frequent problem experienced by wearers of the collection bags is back-flow of urine into the drainage tube, and then the bladder.
An early effort to minimize this problem of back-flow in abdominally worn urine collection bags was to utilize an anti-refluxing flap valve, also known in the art as a non-return valve or flutter valve, and hereinafter referred to simply as an anti-reflux valve, in the form of a pair of inverted V-shaped flexible thermoplastic strips, as described in U.S. Pat. No. 4,449,971. In practice, the inverted U-shaped anti-reflux valve does not function well. In particular, when the urine collection bag is filled and any significant pressure is applied to the bag, pressure is typically applied to the inverted U-shaped valve itself, and it is found that there is unacceptable back-flow.
Later anti-reflux valves for urine collection bags are shown in U.S. Pat. Nos. 4,717,388, 4,772,278, and 4,723,944. The anti-reflux valve in the U.S. Pat. No. 4,717,388 is in the form of a pair of flaps that receive an end of a drainage tube at an upper end of the valve. The two flaps are welded together and taper inwardly along their sides, but are not joined together along their lower ends. The anti-reflux valve of the U.S. Pat. No. 4,772,278 patent is similar to that of the U.S. Pat. No. 4,717,388 patent, but the walls of the valve flare outwardly along the sides toward the lower end. The anti-reflux valve of the U.S. Pat. No. 4,772,278 patent is described to extend below the lower end of a catheter drainage tube by about 65 mm to ensure the valve extends to the region of maximum filling level of the urine collection bag.
The anti-reflux valves described in U.S. Pat. No. 4,723,944 differ from these other prior art anti-reflux valves in several respects. First, the walls of each of the anti-reflux valves of the U.S. Pat. No. 4,723,944 patent extend the full width of the collection bag. Second, instead of a continuous taper, each of the lower side edges or outermost seals of the anti-reflux valves includes an inclined section that leads down to a generally vertical section. One or more additional vertical seals are provided between the outermost vertical seals in the various anti-reflux valves, which form two or more substantially parallel vertical flap valve portions of the anti-reflux valve. Also, the U.S. Pat. No. 4,723,944 patent discusses the use of spot welding to limit the width of the opening of each of the flap valve portions.
It would be desirable for an anti-reflux valve to eliminate virtually all back flow of fluids into drainage tubing, regardless of external pressures applied to the collection bag into which the anti-reflux valve drains. The manner in which the anti-reflux valve of the present invention achieves this desirable result is explained in the following Summary of the Invention, the drawings, and the Detailed Description of the Preferred embodiment.
Urologists have long understood that in order to prevent back flow of urine in the urinary bladder up into the ureters, each ureteral valve in the bladder has to have a length to diameter ratio of 3 to 1 or more. Specifically, this length to diameter ratio represents the length of the portion of the ureter that is exposed to the mucosa, i.e. the lining of the urinary bladder, to the outer diameter of the opening of the ureter. Otherwise, reflux undesirably occurs, which can cause urinary tract infections, permanent damage to the ureter, and even permanent damage to kidney. Kidney damage is possible because pressure in bladder is much greater than pressures the kidneys are designed to take. Without the adequate anti-reflux result achieved by the 3:1 length to diameter ratio of the portion of each ureter under the mucosa, ordinarily high bladder pressures can be reflected in the kidneys.
The anti-reflux valve of the present invention utilizes this naturally-occurring 3 to 1 ratio to advantageously prevent back flow of urine at the entry port of a urine collection bag. In one embodiment of the anti-reflux valve of the present invention, the anti-reflux valve is formed from a single piece of plastomeric material that is folded over to form a flap. Because of the resulting shape, such anti-reflux valves are also called xe2x80x9cduckbill valves.xe2x80x9d The flap is heat sealed along its side edges, and one half of the flap includes an aperture to receive the distal end or port of the inlet connector for connecting a length of drainage tubing, such as catheter or other body fluid drainage tubing, to a collection bag. In conventional anti-reflux valves, only the side edges of the flap are welded together, leaving a lower open end of the flap that allows drainage into the urine collection bag.
In one typical existing anti-reflux valve, the side edges of the flap are tapered, which results in too low a ratio of effective length to diameter. For example, if the tapered portion of the flap is about 16 millimeters in length, as is typical, with an opening of about 18 millimeters across, the ratio is only 1 to 1.125. External pressures exerted on the urine collection bag can thus undesirably cause back flow of urine up into the valve and even back into the urine drainage tube. Instead, the anti-reflux valve of the first embodiment of the present invention includes a relatively longer flap having an elongated passage formed by parallel heat seals between just below the aperture for the inlet connector and the distal opening at the bottom of the side-sealed elongated passage of the valve.
The elongated passage has a length of about 45 millimeters, and the opening at the bottom of the valve, i.e. the diameter of the passage, is about 15 millimeters. The resulting 3 to 1 length to diameter ratio of this effective portion of the anti-reflux valve thus acts very similar to human ureteral anti-reflux mechanisms. Just as urine is prevented from leaving the urinary bladder and flowing up into the ureter, the elongated passage of the anti-reflux valve prevents urine from entering back into the valve or the drainage tube once it has passed into the urine collection bag.
An additional feature of the present invention is to reduce the opening pressure necessary to initiate the flow of urine, or other fluids, through the anti-reflux valve. A means for reducing the opening pressure is to provide a lowermost unsealed portion of each of the front and rear sheets of the anti-reflux valve below the side heat seals of the flap, i.e. below the distal opening at the bottom of the side-sealed elongated passage. Another means of reducing the opening pressure is to prevent undesired curling of the elongated passage by providing one or more spot welds or heat seal tacks to attach only the rear or front sheet of the elongated passage to a wall of the collection bag. These and other features of the present invention are explained in greater detail in the drawings and the detailed description of the preferred embodiments.